This "cross-over" study consists of two parts. In one part, patients will receive topiramate and in the other, an active placebo. An active placebo is a drug that does not work for the problem being studied but whose side effects are like those of the test drug. Diphenhydramine (Benadryl) is the active placebo used in this study. Diphenhydramine is an allergy medication with very mild side effects, such as drowsiness. During both parts of the study-topiramate and placebo-patients will keep a daily log in which they rate their pain, record other procedures they undergo, such as injections and manipulations, and record medication side effects.